Molindone is 3-Ethyl-6,7-dihydro-2-methyl-5-(morpholinomethyl)indol-4(5H)-one (CAS #7416-34-4). The chemical formula of molindone is represented below:

Molindone is a weak base, exhibiting greater solubility in acidic to slightly acidic media than in neutral to slightly alkaline pH values (i.e., the physiologic pH range of the gastro intestinal tract). As a weakly basic drug, molindone is typically used in formulations in the form of a salt. Various prior art methods of manufacturing molindone, such as disclosed in U.S. Pat. No. 3,491,093 and U.S. Pat. No. 3,646,042, are known. However, the prior art methods may result in a drug product that does not meet the modern purity requirements. Thus, what are needed in the art are methods for producing molindone while reducing or eliminating the formation of certain impurities.